Altmeri texts reference many variations of the entrapment spell. Some of those spells, like the early First Era "Aninaire's Tower," create physical fields around their targets. These varieties are unbreachable unless broken by an appropriate amount of force—like conjured stone walls, or shield wards turned inward. The effect differs in strength from spell to spell, but is generally effective for containing the layman prisoner and certainly tougher to break free from than brick and mortar.